1. Field of the Invention
Embodiments of the invention generally relate to a method and apparatus for electro-chemical deposition of a conductive material on a substrate.
2. Background of the Related Art
Sub-quarter micron, multi-level metallization is one of the key technologies for the next generation of ultra large scale integration (ULSI). The multilevel interconnects that lie at the heart of this technology require planarization of interconnect features formed in high aspect ratio apertures, including vias, contacts, lines, plugs and other features. Reliable formation of these interconnect features is very important to the success of ULSI and to the continued effort to increase circuit density and quality on individual substrates and die.
As circuit densities increase, the widths of vias, contacts, lines, plugs and other features, as well as the dielectric materials between them, decrease to less than 250 nanometers, whereas the thickness of the dielectric layers remains substantially constant, with the result that the aspect ratios for the features, i.e., their height divided by width, increases. Due to copper""s good electrical performance at such small feature sizes, copper has become a preferred metal for filling sub-quarter micron, high aspect ratio interconnect features on substrates. However, many traditional deposition processes, such as physical vapor deposition (PVD) and chemical vapor deposition (CVD), have difficulty filling structures with copper material where the aspect ratio exceeds 4:1, and particularly where it exceeds 10:1. As a result of these process limitations, electro-plating, which had previously been limited to the fabrication of lines on circuit boards, is now being used to fill vias and contacts on semiconductor devices.
Metal electro-plating is generally known and can be achieved by a variety of techniques. A typical method generally comprises deposition of a barrier layer over the feature surfaces, followed by deposition of a conductive metal seed layer, preferably copper, over the barrier layer, and then electro-plating a conductive metal over the seed layer to fill the structure/feature. After electro-plating, the deposited layers and the dielectric layers are planarized, such as by chemical mechanical polishing, to define a conductive interconnect feature.
While present day electro-plating cells achieve acceptable results on larger scale substrates, a number of obstacles impair efficient and reliable electro-plating onto substrates having micron-sized, high aspect ratio features. For example, ensuring the availability of deposition material within electrolytes utilized during the plating process often requires the amount of deposition material in the electrolyte to be highly monitored. The cost of monitoring systems disadvantageously contributes to a high cost of system ownership. Moreover, if virgin electrolyte (i.e., fresh or unused) is utilized to minimize contact of contaminants present in recycled electrolyte with the substrate, the volume of costly virgin electrolyte utilized to fill the process cell is great. Thus, a significant quantity of electrolyte is exposed to process related contamination without being utilized during plating operations. This inefficient use of electrolyte unnecessarily drives up processing costs.
Therefore, there is a need for an improved electro-chemical deposition system.
In one aspect of the invention, an apparatus for electro-chemical deposition is generally provided. In one embodiment, a electro-chemical deposition apparatus includes a housing having a substrate support disposed therein and adapted to rotate a substrate. One or more electrical contact elements are disposed on the substrate support. A drive system is disposed proximate the housing. The drive system is magnetically coupled to and adapted to rotate the substrate support.
In another aspect of the invention, a system for electro-chemical deposition is generally provided. In one embodiment, a system for electro-chemical deposition on a substrate includes a first lid, a second lid and a base portion. The first lid has a first lid port and an electrode disposed therein. The second lid has a second lid port. The base portion includes a housing having a substrate support disposed therein. The housing has at least a first port and an upper sealing surface that selectively supports either the first lid or the second lid. A seal is disposed between the upper sealing surface and a lower sealing surface of the first or second lid. The substrate support is adapted to rotate the substrate and includes one or more electrical contact elements.
In another aspect of the invention, a method of plating a substrate is generally provided. In one embodiment, a method of plating a substrate includes the steps of covering a substrate supported within a housing with electrolyte, and displacing a portion of the electrolyte from the housing prior to electrically biasing the substrate, and electrically biasing the substrate.
In another embodiment, a method of plating a substrate includes the steps of supporting a substrate on a substrate support within a housing, covering the supported substrate with electrolyte, magnetically coupling the substrate support with a drive plate disposed exterior to the housing, rotating the drive plate, and electrically biasing the substrate.